Introduction: Icodextrin is a large molecular weight glucose polymer used in the diasylate called Extraneal. It is hydrolysed to oligosaccharides, which are read as glucose by some blood glucose monitoring (BGM) devices resulting in overestimation of capillary blood glucose (CBG) readings. This is dangerous for patients on ambulatory dialysis trying to achieve optimum diabetes control.
Case: A lady with type 1 diabetes using an insulin pump for diabetes control while on ambulatory peritoneal dialysis for end-stage renal disease, had concerns about overestimation of CBG readings by her Contour BGM device and test strip. She used extraneal by day and a glucose-containing dialysate by night. Fear of hypoglycaemia made her keep CBG levels above 14 mmol/l, even though the Contour BGM test strips are noted as safe in such patients. We aimed to reassure her.
Method: She provided CBG readings (pre-breakfast, post-breakfast, pre-lunch, and post-lunch, late afternoon) using her Contour BGM device (glucose dehydrogenase flavin-adenine dinucleotide method). Paired blood samples were also analysed using the One Touch Ultra BGM device (glucose oxidase method) and our laboratory (enzymatic hexokinase method). Agreement with the laboratory method was acceptable if at least 95% of analyser values did not deviate by more than 20%.
Results: Table 1 shows the CBG values from both BGM devices and the corresponding laboratory values. Graphical representation demonstrated that none of the CBG values from both BGM devices deviated by more than 20% from the corresponding reference laboratory values.
|Lab value hexokinase method (mmol/l)||Contor BGM (mmol/l)||One Touch Ultra BGM (mmol/l)|
Conclusion: The Contour BGM device estimated CBG levels accurately when compared to the reference laboratory method and another BGM device: it was unaffected by the Icodextrin-containing dialysate. Her hyperglycaemia was true hyperglycaemia from the glucose-containing dialysate used overnight. She was reassured and could make appropriate changes to her basal rate of insulin with confidence.